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大兴安岭北段奇力滨地区玛尼吐组火山岩年代学、地球化学特征及其地质意义
投稿时间:2020-02-06  修订日期:2020-12-21  点此下载全文
引用本文:
DOI:10.19762/j.cnki.dizhixuebao.2021065
摘要点击次数: 57
全文下载次数: 71
作者单位地址
崔玉斌 北京市地质调查研究院 北京市海淀区通汇路123号
王凯 北京市地质调查研究院 
何付兵 北京市地质调查研究院 
王召林 中国地质科学院地球深部探测中心 北京市西城区百万庄大街26号
王广磊 有色金属矿产地质调查中心 
折士焜 有色金属矿产地质调查中心 
基金项目:本文为中国地质调查局内蒙古鄂伦春自治旗奇力滨地区地质矿产调查项目(编号 12120115031001)成果,受北京市市级职工创新工作室(城市地质、活动构造与监测)资助。
中文摘要:大兴安岭北段奇力滨地区玛尼吐组火山岩主要由安山岩、角闪安山岩和粗安岩组成,化学成分显示其以粗面安山岩为主,少量粗面岩。LA-ICP-MS 锆石U-Pb年龄为141±1.2Ma,表明火山岩形成于早白垩世。岩石地球化学结果表明,奇力滨地区玛尼吐组火山岩SiO2含量介于54.09%~64.89%之间,具有高铝Al2O3(14.67%~17.27%)、高全碱K2O+Na2O(6.33%~8.74%),较低的MgO(0.81%~2.71%)和Mg#(24.84~46.15),为高钾钙碱性火山岩;稀土总量(∑REE)介于146.51×10-6~193.29×10-6,轻重稀土分馏明显(La/Yb)N=8.5~15.52,弱的负铀异常(δEu=0.64~0.96);微量元素以富集Rb、Ba、K等大离子亲石元素(LILE)和轻稀土元素(LREE),亏损Ta、Nb、Ti、Zr、P等高场强元素(HFSE)为特征,同时具有Hf正异常和高Th/Ta、Th/Nb比值,较低的Lu/Yb(0.14~0.16)和Rb/Sr(0.02~0.17)比值。结合前人研究成果,本研究认为奇力滨地区玛尼吐组火山岩岩浆源区为俯冲消减板片流体交代的地幔楔部分熔融,在岩浆上升过程中经历了分离结晶作用和浅部地壳物质的同化混染。该区火山岩形成与蒙古-鄂霍茨克洋闭合造山后的岩石圈伸展和软流圈上隆作用有关。
中文关键词:大兴安岭北段  奇力滨地区  玛尼吐组  锆石U-Pb年龄  地球化学
 
Geochronology and geochemical characteristics of volcanic rocks from the Manitu Formation in Qilibin area, northern Great Xing’an Range and its geological signaficance
Author NameAffiliationAddress
CUI Yubin Beijing Institute of Geological Survey,Beijing 北京市海淀区通汇路123号
WANGKai Beijing Institute of Geological Survey 
HE Fubing Beijing Institute of Geological Survey 
WANG Zhaolin China Deep Exploration Center—SinoProbe Center,China Geological Survey &
amp
amp
Chinese Academy of Geological Sciences 
北京市西城区百万庄大街26号
WANG Guanglei China Non-Ferrous Metals Resource Geological Survey,Beijing 
SHE Shikun China Non-Ferrous Metals Resource Geological Survey,Beijing 
Abstract:The volcanic rocks in Manitu Formation from the Qilibin area,northern Great Xing"an Range are mainly composed of andesite, hungarite,trachyandesite,but they are mainly trachyandesite with minor trachyte based on chemical composition. Zircon U-Pb dating results show that they formed during the Early Cretaceous with the age of 141±1.2 Ma. The geochemical characertistics of the rocks indicate that the volcanic rocks in Manitu Formation from Qilibin area are high in SiO2 (54.09%~64.89%), total alkaline K2O+Na2O (6.33%~8.74%), Al2O3(14.67%~17.27%) and low in MgO (0.81%~2.71%) and Mg# (24.84~46.15), belonging to the calc-alkaline series with high K contents; The rare earth elements analysis show that the total rare earth elements (∑REE) are in 146.51×10-6~193.29×10-6 with insignificant negative Eu anomalise (δEu=0.64~0.96) and intense fractionation between LREE and HREE ((La/Yb)N=8.5~15.52); The trace elements are characterized by LILE (e.g., Rb, Ba, K) and LREE enrichment and HFSE (e.g., Ta, Nb, Ti, Zr, P) depletion, meanwhile, they contain positive Hf anomalies, high ratios of Th/Ta, Th/Nb, low ratios of Lu/Yb (0.14~0.16) and Rb/Sr (0.02~0.17). Combining their geochemical characteristics with previous studies of this area, the magma for the volcanic rocks in Manitu Formation from Qilibin area was derived from the partial melting of the subduction fluid metasomatized mantle wedge, and experienced fractional crystallization and contaminations of crust during the magma ascent. It is possible that these volcanic rocks in Qilibin area were formed by the collision-postorogenic extension of Mongolia-Okhotsc ocean and the upwelling of asthenosphere.
keywords:North part of Great Xing
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